Air line coupler elements for pneumatically operated equipment include couplers that matingly receive plugs. Optimally, the plugs are received in the couplers by mating in a substantially hermetically sealed condition. Plugs are frequently mounted to pneumatic tools such as wrenches, while couplers terminate compressed air hose or tubing.
Plugs and couplers are made in different configurations, that is, plugs and couplers made for industrial uses differ from those made for automotive uses and both types differ from other couplers and plugs made by certain manufacturers, such as ARO™ couplers and plugs from Ingersoll-Rand Company Limited and LINCOLN™ couplers and plugs from Lincoln Industrial Corp. Sometimes plugs and couplers are identified as type A, B, C or D in order to categorize mating components. For example, type A plugs will properly mate with type A couplers but not with types B, C or D couplers. However the type designation is not marked on individual conventional components. In the field, users encounter plugs and couplers from various sources and must use trial and error to determine when a properly mating set of plug and coupler is available. This trial and error results in much wasted time and if unsuccessful, results in use of incompatible plugs and couplers that mate incompletely and therefore leak. A method for a user to quickly visually sort plugs and couplers into properly mating pairs would prevent much wasted effort in the use of pneumatically operated equipment.